GI endoscopy, biopsy and capsule studies

01Purpose and principlesWhat the assessment is for and the core concepts behind it.

Oesophagogastroduodenoscopy directly inspects the oesophagus, stomach and proximal duodenum and allows biopsy, haemostasis, dilation and selected therapy. Colonoscopy examines the colon and terminal ileum when reached, allowing biopsy and polypectomy; flexible sigmoidoscopy is limited to distal bowel but may be sufficient for a focused acute question. Device-assisted enteroscopy reaches deeper small bowel with biopsy and therapy but is specialised. Capsule endoscopy provides a minimally invasive mucosal survey, chiefly of small bowel, and is especially useful after non-diagnostic conventional endoscopy in suspected small-bowel bleeding or selected Crohn's pathways.

Diagnostic yield depends on preparation and a precise referral. Dysphagia requires location and progression; iron-deficiency anaemia requires prior results, coeliac assessment and medicine history; diarrhoea requires duration, inflammation and biopsy question; bleeding requires haemodynamic severity. Endoscopy can miss lesions through retained contents, poor preparation, rapid withdrawal or incomplete reach. A report should document extent, preparation quality, findings, intervention, samples, complications and follow-up owner.

Pre-assessment balances procedural benefit against cardiopulmonary disease, frailty, sleep apnoea, renal or liver dysfunction, pregnancy, allergies, implanted devices and antithrombotic therapy. Unsedated, topical anaesthesia, conscious sedation, inhaled analgesia, deep sedation or general anaesthesia are different choices, not a ladder every patient must climb. Frail or ASA grade 3 or higher patients generally require lower sedative doses and careful increments. Reversal medicines do not substitute for airway skills, monitoring and observation.

Key points

Choose the test by the suspected anatomical site and whether tissue or therapy is needed: capsule endoscopy visualises but cannot biopsy, insufflate, wash or treat.
Urgent endoscopy follows stabilisation in major gastrointestinal bleeding, obstruction or foreign-body emergencies; airway, circulation and senior support come first.
Consent must be procedure- and patient-specific, including alternatives, sedation choices, likely biopsy or therapy and material risks such as bleeding, perforation, aspiration and missed lesions.
Anticoagulant and antiplatelet management depends on both procedural bleeding risk and the patient's thrombotic risk; never advise interruption from a generic rule.
Adequate fasting, bowel preparation and mucosal inspection determine diagnostic quality. An incomplete or poorly prepared test is not simply 'normal'.
Biopsy site, number, orientation and container labelling matter; normal-looking mucosa may still require tissue in coeliac disease, microscopic colitis or eosinophilic disease.
Before capsule endoscopy, assess obstruction or stricture risk and use cross-sectional imaging or a patency capsule when indicated; retention can require device-assisted or surgical retrieval.
Post-procedure severe pain, tachycardia, fever, dyspnoea, haematemesis, melaena or peritonism requires urgent assessment for perforation, bleeding, aspiration or pancreatitis.

02Indications, selection and cautionsWhen it is useful, when urgency changes and important limitations.

Need for emergency therapeutic endoscopyRed flag

Ongoing haematemesis, melaena with shock, variceal bleeding, obstructing food bolus with inability to handle secretions or a dangerous foreign body needs urgent specialist endoscopy after immediate stabilisation.

PerforationRed flag

Severe or increasing chest or abdominal pain, tachycardia, fever, subcutaneous emphysema, dyspnoea or peritonism after endoscopy requires urgent imaging, nil by mouth and senior surgical and endoscopy review.

Significant post-procedure bleedingRed flag

Haematemesis, melaena, haematochezia, dizziness, falling haemoglobin or instability after biopsy, sphincterotomy or polypectomy needs resuscitation and a procedure-specific haemostasis pathway.

Sedation injuryRed flag

Hypoventilation, hypoxia, hypotension, arrhythmia, reduced consciousness or aspiration can occur during and after the procedure, especially with frailty, OSA, liver or renal disease and combined sedatives.

Capsule retention

Failure to observe passage is not diagnostic, but new colicky pain, vomiting or obstruction after capsule ingestion raises retention at a stricture and requires urgent localisation.

03Method and interpretationA systematic approach to the test and its findings.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Upper GI endoscopyFirst step
Why
Inspect and treat oesophageal, gastric and duodenal disease in dysphagia, upper bleeding, mucosal disease, selected anaemia and surveillance indications.
Interpretation and limitations
A complete high-quality examination documents landmarks, mucosal inspection and biopsies. A normal result does not exclude distal small-bowel or extra-luminal disease.
02
Colonoscopy or flexible sigmoidoscopy
Why
Investigate lower bleeding, iron-deficiency anaemia, inflammatory diarrhoea, cancer risk and surveillance, with biopsy or polypectomy.
Interpretation and limitations
Extent and bowel-preparation quality determine confidence. Histologically normal-looking colon can still contain microscopic colitis, so biopsy follows the clinical question.
03
Targeted mucosal biopsy
Why
Sample suspected neoplasia, inflammation, infection or architectural disease using the current BSG, RCPath and local site-and-number protocol.
Interpretation and limitations
Pathology must be linked to site and endoscopic appearance. Villous atrophy, granulomas, dysplasia or eosinophilia all require clinicopathological context.
04
Small-bowel capsule endoscopy
Why
Survey mucosa for a small-bowel bleeding source or selected inflammatory disease after appropriate conventional tests and obstruction-risk assessment.
Interpretation and limitations
Positive lesions need localisation and sometimes enteroscopy; a negative study is weakened by poor views, slow transit or incomplete caecal passage. Capsule cannot biopsy or treat.
05
Cross-sectional enterography or patency assessment
Why
Look for strictures, masses and transmural disease before capsule when obstruction risk exists and determine whether a patency capsule is appropriate.
Interpretation and limitations
A passed patency capsule reduces but does not abolish retention risk. MRI should be avoided until a retained metallic-containing capsule is excluded according to device advice.
06
Pre-procedure safety assessment
Why
Review indication, consent and capacity, fasting or preparation, FBC and coagulation where indicated, renal function for bowel preparation, pregnancy, cardiorespiratory risk and antithrombotic plan.
Interpretation and limitations
Routine blanket blood testing is not a substitute for risk assessment. A high thrombotic-risk stent or anticoagulation indication may change timing or procedure choice.

04Clinical next stepsHow the result changes management or prompts escalation.

01ChooseMatch procedure to questionFirst stepA gastrointestinal symptom or abnormal test warrants luminal investigation.

1Define the anatomical hypothesis, urgency and need for tissue or therapy, and review prior endoscopy and imaging quality.
2AlternativeSelect OGD, colonoscopy, flexible sigmoidoscopy, enteroscopy, capsule or a non-endoscopic alternative with the gastroenterology pathway.
3For capsule, assess stricture and swallowing risk and use enterography or patency testing when indicated.
4State how each possible result will change management and identify who owns histology or delayed capsule reporting.

02PrepareConsent and procedural safetyAn endoscopic or capsule examination has been selected.

1Discuss personalised benefits, uncertainties, alternatives, sedation choices and material risks, checking capacity and communication needs.
2Follow the live BSG and local plan for anticoagulants, antiplatelets and diabetes medicines based on procedure and thrombosis risk; coordinate bridging only when indicated.
3Verify fasting or bowel preparation, renal and cardiopulmonary risks, allergies, implants, transport and post-sedation supervision.
4EscalationUse the safety checklist and confirm biopsy sites, therapeutic equipment and escalation support before starting.

03RescuePost-endoscopy deteriorationPain, bleeding, fever, hypoxia, hypotension, reduced consciousness or obstruction develops during or after a study.

1Use ABCDE, stop the procedure if ongoing, give oxygen and airway support, gain access and start haemorrhage or sepsis resuscitation as indicated.
2Use reversal medicine for clinically important opioid or benzodiazepine effect while maintaining ventilation and monitoring; beware re-sedation.
3Obtain urgent endoscopist, anaesthetic and surgical review and the appropriate CT or radiograph for suspected perforation, aspiration, bleeding or capsule obstruction.
4Document the adverse event, disclosure, follow-up and governance reporting through the local pathway.

05Procedure and medicine safetyRelevant preparation, treatment and contraindications.

Provides anxiolysis, sedation and amnesia for selected endoscopic procedures.

Midazolam

Titrate small intravenous increments to the minimum effective conscious-sedation level under the BSG and local endoscopy protocol; use substantially less in frail, older or comorbid adults.

Respiratory depression, hypotension, paradoxical agitation and prolonged effect, amplified by opioids, liver disease and renal impairment. Requires monitoring, trained airway support and post-procedure observation.

Provides short-acting analgesia for uncomfortable diagnostic or therapeutic procedures.

Fentanyl

Use small titrated intravenous doses only within the local endoscopy-sedation protocol, accounting for age, frailty, opioid exposure and concurrent benzodiazepine.

Respiratory depression, chest-wall rigidity at higher rapid doses, nausea and synergistic sedation. Naloxone may wear off first; continue monitoring.

Reverses benzodiazepine-induced respiratory or consciousness impairment while airway support continues.

Flumazenil

Titrated intravenous reversal regimen from the current BNF and emergency protocol for clinically significant benzodiazepine sedation, not routine wake-up.

Can precipitate seizures or withdrawal in dependent patients or mixed overdoses and has a shorter duration than some benzodiazepines, so re-sedation monitoring is essential.

Reverses clinically important opioid-induced respiratory depression.

Naloxone

Titrate intravenous doses to restore adequate ventilation rather than full pain reversal, following current BNF and local emergency guidance; repeat or infuse if re-sedation occurs.

Acute withdrawal, severe pain, hypertension or arrhythmia can follow excessive reversal. Its duration may be shorter than the opioid; airway care and observation remain mandatory.

06Risks, monitoring and follow-upComplications, safety checks and further assessment.

During sedated endoscopy monitor consciousness, pulse, blood pressure, oxygen saturation and respiration at the locally required interval; use capnography and enhanced monitoring for deeper sedation or high risk.
Confirm adequate recovery, stable observations, pain control, oral safety and escort or supervision arrangements before discharge.
Provide written advice on expected minor symptoms and urgent red flags, including bleeding, severe pain, fever, breathlessness and inability to pass a capsule with obstructive symptoms.
Track histology, polyp pathology, microbiology and capsule results to a named clinician and communicate the management plan.
Audit preparation quality, completion, lesion detection, complications, sedation use and patient experience according to BSG and JAG standards.
After reversal medicine, observe long enough for recurrent respiratory depression and apply the local discharge restriction.
For capsule, document completion into caecum, preparation, transit, retention risk and whether subsequent MRI is safe.

07Special situationsVariants, exceptions and circumstances that change the usual approach.

Normal mucosa may need biopsy

Microscopic colitis, coeliac disease and some eosinophilic conditions can be histological despite subtle or absent visual change.

Capsule is a camera only

It cannot control its speed, wash residue, insufflate, biopsy or treat. A positive result frequently starts a second procedural decision.

Antithrombotic plans are two-dimensional

A low-risk biopsy and a high-risk polypectomy differ, but so do atrial fibrillation and a recent coronary stent. Both procedure and patient risk determine the plan.

Preparation is part of accuracy

A 'normal' poorly prepared colon or incomplete capsule has limited negative value. Reports must state quality and completion.

Reversal does not end the emergency

Flumazenil and naloxone can wear off before the sedative. Ventilation, monitoring and investigation of other causes continue.

08Common pitfallsFrequent interpretation and management errors.

01
Referring for capsule endoscopy when biopsy or immediate therapy is required.
02
Sending a capsule through a suspected stricture without patency or cross-sectional assessment.
03
Using a generic instruction to stop anticoagulation without considering thrombosis risk.
04
Calling an incomplete or poorly prepared examination normal.
05
Taking biopsies without clearly labelled anatomical sites or a clinical question.
06
Treating flumazenil or naloxone as a substitute for airway management and observation.